Broken emma-examples link in README

[manuzhang]

This link https://github.com/emmalanguage/emma/blob/master/emma-examples/emma-examples-library/src/main/scala/org/emmalanguage/examples doesn't exist.

[aalexandrov]

Good catch, the current path is https://github.com/emmalanguage/emma/tree/master/emma-examples/src/main/scala/org/emmalanguage/examples (the emma-examples-library part should be omitted).